Variations

Make a few copies of the orb. Select the colored circle (in this case red) and change its color. You instantly get complete orbs with different colors.

Is possible to put even some content inside the orb: in this case I used a letter made with the text tool, added a highlight, a darken area and a shadow. Group them (Object > Group, Ctrl + G), move over the orb and lower their position down the stack (above the colored circle but under the various light or dark areas).